In general, vehicle drivelines transmit torque from a vehicle's engine to its wheels. Automotive drivelines sometimes include power transfer units (PTUs, also known as power take-off units) for selectively distributing torque among shafts in the drivelines. The PTUs are often equipped in four-wheel and all-wheel drive driveline configurations. A power transfer unit typically consists of a housing that encloses and supports gear assemblies, shafts, and bearings, among other possible components. Oil is ordinarily kept in the housing to lubricate the gear assemblies as they rotate and mesh during operation of the driveline, and to lubricate the bearings and other components. The housing is typically filled with oil only partway and not fully, as oil usually makes its way to all of the components when it is sloshed and splashed and slung around in the housing during operation.